How power-generating glass helps boost green energy and urban design

In the Chongli District of Zhangjiakou, Hebei Province, maintaining the fountain landscape in a pocket park sustainably is a big challenge, especially with winter temperatures that can plummet to as low as minus 30 degrees Celsius.

This challenge was addressed by implementing underwater photovoltaic technology using cadmium telluride (CdTe). A total of 420 tiles were installed at the pool's bottom, capable of producing around 25,000 kilowatt-hours of electricity annually. This power generation offsets the electricity demands for heating, fountains and lighting during the winter, making the system efficient and smartly managed.

Given that photovoltaic power generation is a crucial source of sustainable electricity, aiding in the reduction of carbon dioxide emissions, the application of these photovoltaic floor tiles not only solves operational problems but also promotes green, pollution-free energy.

The CdTe used in the tiles is a stable crystalline compound known for its high potential in converting sunlight into electricity. When sunlight hits the thin CdTe layer, it triggers particle movement within this layer, facilitating electricity generation. A layer of CdTe just one micrometer thick can absorb over 90 percent of visible light, demonstrating its efficiency in capturing solar energy.

Building on this efficiency, the technology's use goes beyond conventional panels to include integration into glass. The electricity-generating capability of this glass is made possible through a 4-micrometer-thick layer of CdTe photovoltaic film embedded within it. At first glance, these photovoltaic panels appear as transparent as glass, but a closer look reveals neatly arranged thin lines inside, indicating the photovoltaic material at work.

Such technological innovation yields impressive results: a single 2-square-meter piece of power-generating glass can produce 270 kilowatt-hours of electricity annually, even in low indoor light conditions. This means that just two or three pieces of this glass could meet the annual electricity consumption of an average household, indicating the technology's potential to contribute to sustainable energy solutions for residential settings.

Applications for sustainable urban future

Sichuan is one of China's largest bases for clean energy. Last year, its capital Chengdu's annual production capacity for CdTe power-generating glass reached 100 megawatts. This capacity led to an average annual power generation of over 110 million kilowatt-hours, saving nearly 40,000 tonnes of standard coal and cutting carbon dioxide emissions by almost 120,000 tonnes.

Back in 2018, the first large CdTe solar panel production line in southwestern China was launched in Sichuan Province, marking a step in transforming flat glass from a mere building material into a multifunctional one that can generate electricity and filter light.

"Unlike traditional photovoltaic technology, which embeds cells within the glass, the method we developed involves depositing CdTe directly onto the glass surface," said Pan Jingong, an official at CNBM (Chengdu) Optoelectronic Materials Co., Ltd., a high-tech enterprise affiliated with China National Building Material Group, which is at the forefront of advancing photovoltaic technology.

Beyond its high absorption coefficient and conversion efficiency, power-generating glass stands out from traditional photovoltaic panels, which require flat installation. It can be installed on walls, enabling it to produce electricity in the presence of light. This versatility broadens the applications of photovoltaic technology in urban and architectural design, furthering the development of sustainable energy solutions.

Additionally, incorporating CdTe enhances the glass's strength. The highly stable crystal structure allows it to be safely encapsulated within the power-generating glass for many years, ensuring durability and efficiency.

"After conducting the 45-kg lead ball experiment, the appearance of the cadmium telluride glass remained intact," said Wang Yiren, the company's market consultant. "Throughout this process, its power generation performance maintained remarkable stability."

As photovoltaic technology progresses, CdTe power-generating glass is being increasingly adopted in various structures. For instance, the roof of the Hangzhou Convention and Exhibition Center generates over 700,000 kWh of electricity each year, covering its annual lighting needs. Beyond buildings, this technology extends to cars and walls, transforming glass surfaces into potential power stations.

"The essence of power-generating glass lies in its coating of cadmium telluride thin-film solar cells, which allow light to pass through while generating electricity, and our current goal is to transform buildings into electricity-generating entities," said Wu Xuanzhi, an official with a power generation glass manufacturing firm based in Hangzhou. "We're focused on developing new products and markets, aiming to price our products affordably so they are accessible to the general public."

(Cover designed by Liu Shaozhen)